by Michael Winter, USA TODAY

by Michael Winter, USA TODAY

The Islamic State wants more than $6 million to free an American woman the Muslim extremists kidnapped a year ago while she did humanitarian work in Syria, according to her family, U.S. officials and news reports.

Citing concern for her safety in the wake of the militants' execution of journalist James Foley last week, the 26-year-old woman's family and the State Department asked that she not be identified. The three humanitarian groups she worked for also were not named.

She is the third American known to have been abducted in Syria by the Islamic State.

ABC and NBC reported the Islamic State wants $6.6 million to release the woman, who was captured Aug. 4, 2013. The extremists want to exchange her for Pakistani Aafia Siddiqui, an MIT-trained neuroscientist. A U.S. jury convicted him in 2010 of trying to kill U.S. officials.

ABC said various extremist groups critical of U.S. actions in Pakistan, Afghanistan and the Middle East have regularly called for his release.

The Siddiqui family has been "traumatized by the thoughts that someone else could be harmed in the name of Aafia," said family spokesman Mauri Saalakhan, who spoke Monday at a news conference.

Foley of Rochester, N.H., was captured in November 2012 while on assignment for GlobalPost. The extremists demanded 100 million euros - $132.5 million - for his release, said the CEO and co-founder of the Boston-based online publication.

The Aug. 19 video showing his grisly death ends with another missing U.S. freelancer, Steven Sotloff of Miami, and warns President Obama that Sotloff's life "depends on your next decision."

Sunday, American freelance writer Peter Theo Curtis, 45, was freed after almost two years imprisoned by the Nusra Front, an affiliate of al-Qaeda in Syria that split with the Islamic State this year.

His release was brokered by Qatar, which has helped negotiate the release of other kidnapped Westerners in exchange for huge ransoms. His family said Qatari officials told them his release was negotiated "on a humanitarian basis" and no ransom was paid.